The P3P is the first automated and tailored intervention for men with localized prostate cancer (LPC) to demonstrate efficacy in a U.S. sample. We have evidence that the P3P decreases decisional conflict; men are able to, in their words, choose the best treatment for me. Yet as with many decision support technologies and interventions, deployment as an integral component of cancer clinical care has not been established, notably with regard to feasibility as routine practice and to costs. LPC can be treated with one or more modalities including observation alone, surgery, cryosurgery, hormonal therapy, brachytherapy, or external beam radiation therapy. There are few findings from randomized studies of these treatment modalities in North American settings that adequately compare the complications of sexual, bladder, and bowel dysfunction. For many years to come, men will hear clinician recommendations but also will be asked to make major choices about prostate cancer treatments. These decisions can dramatically change men's lives. The purpose of this hybrid effectiveness-implementation study is to deploy and evaluate an efficacious, patient-centered, treatment decision technology in geographically, ethnically and racially diverse health care settings as a means to support men with newly diagnosed LPC. We will collect resource costs associated with preparation for the treatment decision using the P3P program versus standard practice. Metrics associated with viability of P3P implementation will be collected in each of three health network settings which serve a diverse population of men with prostate cancer. PUBLIC HEALTH RELEVANCE: Localized prostate cancer can be treated with one or more modalities including observation alone, surgery, cryosurgery, hormonal therapy, brachytherapy, or external beam radiation therapy~ and there is no strong evidence for which treatment is most efficacious. For many years to come, men will hear clinician recommendations but also will be asked to make major choices about prostate cancer treatments. The purpose of this hybrid effectiveness-implementation study is to further evaluate an efficacious, patient- centered, decision support technology in geographically, ethnically and racially diverse health care settings as a means to support men with newly diagnosed LPC~ and to study how it is implemented as routine care in these networks.